A procedure for the determination of calcium and magnesium with EDTA in solutions containing iron, aluminum, manganese and copper was studied. The following procedure is proposed for 0.05 Nnitric acid extracts of soils: a)precipitation of iron, aluminum and manganese with ammonium hydroxide and hydrogen peroxide; b)calcium titration with EDTA solution at pH higher than 12, using murexide as dye; c) destruction of the murexide by acidification and heating; d)copper complexing by sodium diethyldithyocarbamate and magnesium determination with EDTA, at pH 10, using Eriochrome Black T as dye.